adding net48 to the benchmark project targets

[lipchev]

• updating the FromString benchmarks (multi-target)
• updating the results for FromString and BasicMath (multi-target)

I've got some very interesting charts, please merge this before the PR for #56 so that it would be easier to compare (I've got the same set of results there as well).

.. more info to come

[lipchev]

Have a look at the difference between simply parsing a string as BigInteger

[MemoryDiagnoser]
[ShortRunJob(RuntimeMoniker.Net48)]
[ShortRunJob(RuntimeMoniker.Net80)]
public class BigIntegerBenchmarks {

    [Benchmark(Baseline = true)]
    public BigInteger Parsing_12345_with_sign() {
        return BigInteger.Parse("-12345789987654321", NumberStyles.AllowLeadingSign);
    }

    [Benchmark]
    public BigInteger Parsing_12345_and_negate() {
        return -BigInteger.Parse("12345789987654321", NumberStyles.None);
    }
    
    [Benchmark]
    public BigInteger Parsing_12345_as_integer() {
        return BigInteger.Parse("-12345789987654321", NumberStyles.Integer);
    }
    
    [Benchmark]
    public BigInteger Parsing_12345_as_number() {
        return BigInteger.Parse("-12345789987654321", NumberStyles.Number);
    }
    
    [Benchmark]
    public BigInteger Parsing_12345_as_any() {
        return BigInteger.Parse("-12345789987654321", NumberStyles.Any);
    }

    [Benchmark]
    public BigInteger Parsing_0_12345_with_sign() {
        return BigInteger.Parse("-0000000000000000000012345789987654321", NumberStyles.AllowLeadingSign);
    }

    [Benchmark]
    public BigInteger Parsing_0_12345_and_negate() {
        return -BigInteger.Parse("0000000000000000000012345789987654321", NumberStyles.None);
    }

    [Benchmark]
    public BigInteger Parsing_0_12345_as_integer() {
        return BigInteger.Parse("-0000000000000000000012345789987654321", NumberStyles.Integer);
    }
    
    [Benchmark]
    public BigInteger Parsing_0_12345_as_number() {
        return BigInteger.Parse("-0000000000000000000012345789987654321", NumberStyles.Number);
    }
    
    [Benchmark]
    public BigInteger Parsing_0_12345_as_any() {
        return BigInteger.Parse("-0000000000000000000012345789987654321", NumberStyles.Any);
    }
}

BenchmarkDotNet v0.13.12, Windows 10 (10.0.19045.4291/22H2/2022Update)
AMD Ryzen 9 7900X, 1 CPU, 24 logical and 12 physical cores
.NET SDK 8.0.204
  [Host]                      : .NET 8.0.4 (8.0.424.16909), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  ShortRun-.NET 8.0           : .NET 8.0.4 (8.0.424.16909), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  ShortRun-.NET Framework 4.8 : .NET Framework 4.8.1 (4.8.9232.0), X64 RyuJIT VectorSize=256
IterationCount=3  LaunchCount=1  WarmupCount=3

Method	Job	Runtime	Mean	Error	StdDev	Ratio	RatioSD	Gen0	Allocated	Alloc Ratio
Parsing_12345_with_sign	ShortRun-.NET 8.0	.NET 8.0	100.59 ns	5.574 ns	0.306 ns	1.00	0.00	0.0143	240 B	1.00
Parsing_12345_and_negate	ShortRun-.NET 8.0	.NET 8.0	88.97 ns	15.474 ns	0.848 ns	0.88	0.01	0.0143	240 B	1.00
Parsing_12345_as_integer	ShortRun-.NET 8.0	.NET 8.0	99.17 ns	9.046 ns	0.496 ns	0.99	0.01	0.0143	240 B	1.00
Parsing_12345_as_number	ShortRun-.NET 8.0	.NET 8.0	89.47 ns	6.645 ns	0.364 ns	0.89	0.00	0.0143	240 B	1.00
Parsing_12345_as_any	ShortRun-.NET 8.0	.NET 8.0	100.88 ns	18.144 ns	0.995 ns	1.00	0.01	0.0143	240 B	1.00
Parsing_0_12345_with_sign	ShortRun-.NET 8.0	.NET 8.0	134.61 ns	22.490 ns	1.233 ns	1.34	0.01	0.0143	240 B	1.00
Parsing_0_12345_and_negate	ShortRun-.NET 8.0	.NET 8.0	125.96 ns	38.847 ns	2.129 ns	1.25	0.02	0.0143	240 B	1.00
Parsing_0_12345_as_integer	ShortRun-.NET 8.0	.NET 8.0	140.12 ns	37.378 ns	2.049 ns	1.39	0.02	0.0143	240 B	1.00
Parsing_0_12345_as_number	ShortRun-.NET 8.0	.NET 8.0	137.54 ns	16.836 ns	0.923 ns	1.37	0.01	0.0143	240 B	1.00
Parsing_0_12345_as_any	ShortRun-.NET 8.0	.NET 8.0	138.55 ns	17.770 ns	0.974 ns	1.38	0.01	0.0143	240 B	1.00
Parsing_12345_with_sign	ShortRun-.NET Framework 4.8	.NET Framework 4.8	980.73 ns	139.349 ns	7.638 ns	1.00	0.00	0.1106	706 B	1.00
Parsing_12345_and_negate	ShortRun-.NET Framework 4.8	.NET Framework 4.8	999.74 ns	127.631 ns	6.996 ns	1.02	0.02	0.1106	706 B	1.00
Parsing_12345_as_integer	ShortRun-.NET Framework 4.8	.NET Framework 4.8	992.41 ns	98.195 ns	5.382 ns	1.01	0.00	0.1106	706 B	1.00
Parsing_12345_as_number	ShortRun-.NET Framework 4.8	.NET Framework 4.8	989.30 ns	118.202 ns	6.479 ns	1.01	0.00	0.1106	706 B	1.00
Parsing_12345_as_any	ShortRun-.NET Framework 4.8	.NET Framework 4.8	1,012.72 ns	83.545 ns	4.579 ns	1.03	0.01	0.1106	706 B	1.00
Parsing_0_12345_with_sign	ShortRun-.NET Framework 4.8	.NET Framework 4.8	1,020.56 ns	34.931 ns	1.915 ns	1.04	0.01	0.1106	706 B	1.00
Parsing_0_12345_and_negate	ShortRun-.NET Framework 4.8	.NET Framework 4.8	1,024.28 ns	94.638 ns	5.187 ns	1.04	0.01	0.1106	706 B	1.00
Parsing_0_12345_as_integer	ShortRun-.NET Framework 4.8	.NET Framework 4.8	1,016.82 ns	58.949 ns	3.231 ns	1.04	0.01	0.1106	706 B	1.00
Parsing_0_12345_as_number	ShortRun-.NET Framework 4.8	.NET Framework 4.8	1,016.81 ns	46.941 ns	2.573 ns	1.04	0.01	0.1106	706 B	1.00
Parsing_0_12345_as_any	ShortRun-.NET Framework 4.8	.NET Framework 4.8	1,025.18 ns	120.029 ns	6.579 ns	1.05	0.01	0.1106	706 B	1.00

I guess upgrading really pays off 😄